Field of the Invention
Embodiments of the invention generally relate to optoelectronic semiconductor devices such as photovoltaic devices including solar cells, and methods for fabricating such optoelectronic devices.
Description of the Related Art
As fossil fuels are being depleted at ever-increasing rates, the need for alternative energy sources is becoming more and more apparent. Energy derived from wind, from the sun, and from flowing water offer renewable, environment-friendly alternatives to fossil fuels, such as coal, oil, and natural gas. Being readily available almost anywhere on Earth, solar energy may someday be a viable alternative.
To harness energy from the sun, the junction of a solar cell absorbs photons to produce electron-hole pairs, which are separated by the internal electric field of the junction to generate a voltage, thereby converting light energy to electric energy. The generated voltage can be increased by connecting solar cells in series, and the current may be increased by connecting solar cells in parallel. Solar cells may be grouped together on solar panels. An inverter may be coupled to several solar panels to convert DC power to AC power.
Nevertheless, the currently high cost of producing solar cells relative to the low efficiency levels of contemporary devices is preventing solar cells from becoming a mainstream energy source and limiting the applications to which solar cells may be suited. During conventional fabrication processes for photovoltaic devices, metallic contacts are often deposited with a vapor deposition process, and usually heated to temperatures of over 300° C. during thermal anneal processes. These high temperature processes are generally expensive due to the excessive consumption of time and energy. Also, the high temperature processes often damage sensitive materials contained within the photovoltaic device.
Accordingly, there is a need for optoelectronic devices with increased efficiency and methods for fabricating such optoelectronic devices at reduced costs when compared to conventional solar cells.